Slow response to entecavir treatment in treatment-naive HBV patients is conditioned by immune response rather than by the presence or selection of refractory variants

Molecular cloning and phenotypic analysis of drug-resistance mutants with relevant S-region variants of HBV for a patient during 189-month anti-HBV treatment

BACKGROUND

A unique chronic hepatitis B patient was followed over 189 months of nucleoside/nucleotide analogue (NA) therapies with the analysis of multiple drug-resistance HBV mutants.

METHODS

Clonal sequencing (≥20 clones/sample) was performed on sera sampled at 41 time points, and the phenotypic features of eight representative mutants were analysed.

RESULTS

Lamivudine (LAM)-, adefovir dipivoxil (ADV)-, entecavir (ETV)- and repeat ADV-resistance mutants emerged upon individual sequential NA monotherapy. The efficacy of NA combination rescue therapies ranked as LAM+ADV < ETV+ADV < ETV+ tenofovir disoproxil fumarate (TDF). Specifically, LAM+ADV and ETV+ADV suppressed viral loads to <100 IU/ml for a long period of time, either with or without late stage HBV DNA fluctuations. Furthermore, ETV+TDF suppressed the viral load to <10 IU/ml. During the LAM+ADV and ETV+ADV combination therapies, ETV-resistance mutants dominated at most time points, and multidrug-resistance (MDR) mutants that harboured LAM-, ETV- and ADV-resistance mutations were intermittently detected. Interestingly, the rtA181T-causative sW172stop to sW172non-stop mutation transition was observed at HBV DNA fluctuations. In a phenotypic analysis, two MDR strains had cross-resistance to LAM, ETV and ADV, and a lower susceptibility to TDF (<10-fold decrease compared with the wild-type strain). In contrast, the natural replication capacity was inversely associated with the number of primary resistant mutations which would limit MDR mutant development.

CONCLUSIONS

Taken together, viral drug susceptibility, replication capacity, and perhaps immunological adaptation may play coordinated roles in the fitness of drug-resistance mutants. ETV+TDF therapy is the preferred option for treating chronic hepatitis B patients with multiple drug failure.

A Public Health Analysis on Gaps in Disease Monitoring and Opportunities for Improved Care for the Management of Hepatitis B and C

Hepatitis B and Hepatitis C have been major disease-causing agents among humans since they were discovered in the 1960s. Both cause jaundice-like symptoms initially but their prognosis and treatment are somehow different and depend upon many demographic details, such as the age and susceptibility of the patients and any other comorbid conditions. They clinically present primarily with hepatitis and can have many adverse effects or even be life-threatening at times, if not treated properly. However, their epidemiological background and findings in terms of morbidity, mortality, and case fatality rates are different. The disease burden, impact on the healthcare system, and prevention of the two diseases are quite different. The treatment and management options along with the prevention and control measures share unique strategies for handling the two diseases. The purpose of this review is to highlight the gaps in disease monitoring and to find ways and opportunities that can lead to improved care and better management of Hepatitis B and C locally and globally. Online databases were searched and peer-reviewed articles were selected. Key issues identified were lack of education globally in resource-limited settings, leading to a decreased understanding of the potential hazards associated with needle sharing and lack of access to healthcare because of a lack of insurance. The failure of compliance with vaccination leads to an increase in mother-to-child transmission (MTCT)-related infections. Increased global travel demands a systematic program in most immigrant-receiving countries to screen for hepatitis B virus (HBV)/hepatitis c virus (HCV) infections. Delayed U.S. Food and Drug Administration (FDA) licensing for new drugs hampers the treatment of chronic Hepatitis-B (CHB) among children. With the advancement in science, an effective vaccine against HCV will definitely help in eradicating the infection.

How viral genetic variants and genotypes influence disease and treatment outcome of chronic hepatitis B. Time for an individualised approach?

Chronic hepatitis B virus (HBV) infection remains a global problem. Several HBV genotypes exist with different biology and geographical prevalence. Whilst the future aim of HBV treatment remains viral eradication, current treatment strategies aim to suppress the virus and prevent the progression of liver disease. Current strategies also involve identification of patients for treatment, namely those at risk of progressive liver disease. Identification of HBV genotype, HBV mutants and other predictive factors allow for tailoured treatments, and risk-surveillance pathways, such as hepatocellular cancer screening. In the future, these factors may enable stratification not only of treatment decisions, but also of patients at risk of higher relapse rates when current therapies are discontinued. Newer technologies, such as next-generation sequencing, to assess drug-resistant or immune escape variants and quasi-species heterogeneity in patients, may allow for more information-based treatment decisions between the clinician and the patient. This article serves to discuss how HBV genotypes and genetic variants impact not only upon the disease course and outcomes, but also current treatment strategies. Adopting a personalised genotypic approach may play a role in future strategies to combat the disease. Herein, we discuss new technologies that may allow more informed decision-making for response guided therapy in the battle against HBV.

Prevalence of hepatitis B antiviral drug resistance variants in North American patients with chronic hepatitis B not receiving antiviral treatment

Antiviral drug resistance hepatitis B virus (HBV) variants (HBV-DR) occur spontaneously in chronic hepatitis B (CHB) patients and after exposure to nucleos(t)ide analogues (NUCs). We determined the prevalence of HBV-DR variants among participants of the Hepatitis B Research Network (HBRN) Cohort Study conducted at 21 sites in the United States (US) and Canada. Samples obtained from 1342 CHB participants aged ≥18 years, and who were currently not receiving NUCs, were tested for HBV-DR variants by Sanger sequencing. In addition, next generation sequencing (NGS) was used to characterize HBV-DR variants from 66 participants with and 66 participants with no prior NUC exposure matched for HBV genotype and HBV DNA level. Half the participants were men, 75% Asian, 26% HBeAg positive. Primary HBV-DR variants were detected by Sanger sequencing in 16 (1.2%) participants: 2/142 (1.4%) with and 14/1200 (1.2%) without prior NUC exposure; only 1 of these 16 had a secondary variant. In total, 23 (1.7%) participants had secondary variants, including 1 with prior NUC experience. In the subset of 132 participants, NGS detected HBV-DR variants in a higher proportion of participants: primary variants in 18 (13.6%) (8 [12.1%] with, and 10 [15.2%] without prior NUC therapy) and secondary variants in 10 (7.6%) participants. Based on Sanger sequencing, prevalence of primary HBV-DR variants is low (1.2%) among adults with CHB in US/Canada. The similar low prevalence of HBV-DR variants in participants with and without NUC treatment suggests transmission of these variants is uncommon.

HBV quasispecies composition in Lamivudine-failed chronic hepatitis B patients and its influence on virological response to Tenofovir-based rescue therapy

The present study sought to evaluate the structure of HBV quasispecies in Lamivudine (LMV)-failed chronic hepatitis B (CHB) patients and its impact in defining the subsequent virological responses to Tenofovir (TDF)-based rescue-therapy. By analyzing HBV clones encompassing reverse transcriptase (RT) and surface (S) region from LMV-failed and treatment-naïve CHB patients, we identified 5 classical and 12 novel substitutions in HBV/RT and 9 substitutions in immune-epitopes of HBV/S that were significantly associated with LMV failure. In silico analysis showed spatial proximity of some of the newly-identified, mutated RT residues to the RT catalytic centre while most S-substitutions caused alteration in epitope hydrophobicity. TDF administration resulted in virological response in 60% of LMV-failed patients at 24-week but non-response in 40% of patients even after 48-weeks. Significantly high frequencies of 6 S-substitutions and one novel RT-substitution, rtH124N with 6.5-fold-reduced susceptibility to TDF in vitro, were noted at baseline in TDF non-responders than responders. Follow-up studies depicted greater evolutionary drift of HBV quasispecies and significant decline in frequencies of 3 RT and 6 S-substitutions in responder-subgroup after 24-week TDF-therapy while most variants persisted in non-responders. Thus, we identified the HBV-RT/S variants that could potentially predict unfavorable response to LMV/TDF-therapy and impede immune-mediated viral clearance.

Combined Analysis of the Prevalence of Drug-Resistant Hepatitis B Virus in Antiviral Therapy-Experienced Patients in Europe (CAPRE)

BACKGROUND

European guidelines recommend treatment of chronic hepatitis B virus infection (CHB) with the nucleos(t)ide analogs (NAs) entecavir or tenofovir. However, many European CHB patients have been exposed to other NAs, which are associated with therapy failure and resistance. The CAPRE study was performed to gain insight in prevalence and characteristics of NA resistance in Europe.

METHODS

A survey was performed on genotypic resistance testing results acquired during routine monitoring of CHB patients with detectable serum hepatitis B virus DNA in European tertiary referral centers.

RESULTS

Data from 1568 patients were included. The majority (73.8%) were exposed to lamivudine monotherapy. Drug-resistant strains were detected in 52.7%. The most frequently encountered primary mutation was M204V/I (48.7%), followed by A181T/V (3.8%) and N236T (2.6%). In patients exposed to entecavir (n = 102), full resistance was present in 35.3%. Independent risk factors for resistance were age, viral load, and lamivudine exposure (P < .001).

CONCLUSIONS

These findings support resistance testing in cases of apparent NA therapy failure. This survey highlights the impact of exposure to lamivudine and adefovir on development of drug resistance and cross-resistance. Continued use of these NAs needs to be reconsidered at a pan-European level.